含逆变型分布式电源的配电网正序阻抗纵联保护

逆变型分布式电源区别于传统电源的故障特性导致传统电流保护难以快速可靠切除故障,也影响了现有输电网保护原理直接应用于配电网的动作性能。借鉴电流差动保护原理思想,定义了正序差动阻抗,理论分析了其在区内外故障时的幅值差异,提出了一种适用于有源配电网的正序阻抗差动保护原理。为进一步改善保护性能,有效应对分支负荷的影响,构造了带制动特性的动作判据。针对区内三相金属性短路故障时保护存在的死区问题,利用故障时正序阻抗与正序电流幅值特征构造了辅助判据。与传统电流差动保护相比,所述方法无需两端数据同步采样,对通信要求较低。仿真结果验证了保护原理的有效性。

Pilot Protection of Positive Sequence Impedance for Distribution Network with Inverter-based Distributed Generator

The fault characteristics of the inverter-based distributed generator(IBDG)differ from those of traditional resources, which makes it difficult for traditional current relay to clear fault fast and reliably. Also affected is the action performance of the existing transmission line protection principle directly used in distribution network with IBDG. By drawing on current differential protection for reference, the amplitudes of the defined positive sequence differential impedance for the internal and external fault are analyzed, and a novel positive sequence differential impedance protection principle is proposed to account for the impedance amplitude difference. To further improve the performance, an operation criterion with braking characteristic is constructed to overcome the adverse effects of load branch. An auxiliary criterion based on the amplitude of positive sequence impedance and current is formulated for internal three-phase short circuit faults without transition resistance. Compared with the traditional current differential protection, the proposed protection strategy has no need for synchronized measurement. The feasibility of protection scheme is verified by simulation results. This work is supported by National High Technology Research and Development Program of China(863 Program)(No. 2012AA050213)and Shandong Province Key Plan of Research and Development(No. 2015GGX101011).